To avoid the necessity of precisely positioning a towing vehicle, or tractor, in relation to the trailer in order to couple the two together, it has been suggested in the prior art that an extensible and swingable hitch be provided on one of the vehicles which will enable the tractor to be only approximately positioned, the two vehicles then connected, and in various ways the hitch is then centered and locked for further towing operations. Representative prior art patents disclosing such hitches are as follows:
U.S. Pat. No. 2,973,971 PA1 U.S. Pat. No. 3,083,986 PA1 U.S. Pat. No. 3,329,445 PA1 U.S. Pat. No. 3,397,900 PA1 U.S. Pat. No. 3,521,908 PA1 U.S. Pat. No. 3,612,576 PA1 U.S. Pat. No. 3,698,739
Of the foregoing patents, U.S. Pat. No. 3,698,739, as well as several others, enable the hitch to be centered following coupling of the tractor and trailer by backing the tractor toward the trailer, causing cooperating parts of the hitch to react in such fashion that the hitch is forced into alignment with the longitudinal axis of the tractor or trailer so that the hitch may be locked for forward towing operations. Each of these prior art efforts contains some meritorious features, as well as some disadvantages as will be apparent to those skilled in the art.